Weighted Exam Average Calculator
Your subject mark from a list of assessments and their weights — with what each one actually contributed.
A weighted average multiplies each mark by its weight and divides by the total weight.
How the weighted exam average calculator works
A weighted average multiplies each mark by its weight and divides by the total weight. If the weights sum to 100 the division is invisible, which is why people forget it is there and get confused when the weights sum to 90 because one assessment has not happened yet.
This handles that case: it reports the mark on completed work separately from the mark on the whole subject, which are different numbers and answer different questions.
Formula: weighted average = Σ(mark × weight) / Σ(weight)
Worked examples
| Inputs | Weighted average | Note |
|---|---|---|
| Four assessments summing to 100% | 67.25% | 67.05% |
| Weights that do not sum to 100 | 73.417% | divides by 60 |
| Equal weights | 69% | matches the plain average |
FAQFrequently asked questions
How do I calculate a weighted average?
Multiply each mark by its weight, add them up, and divide by the total weight.
What if my weights do not add to 100?
The division handles it. The result is your mark on the work completed so far, which is a different question from your final subject mark.
Why is my weighted average lower than my plain average?
Because your weaker marks fell on the heavier assessments. The difference row shows exactly how much that cost.
Does a 0 weight assessment matter?
Not to the average. It contributes nothing and does not change the divisor.
How do I use this to plan?
Enter the marks you have plus a guess for what is left. The weight on the remaining work tells you how much it can still move the total.
Where these figures come from
- Brysbaert (2019), Journal of Memory and Language — How many words do we read per minute? — the 238 wpm silent reading rate, from 190 studies
- Office for Students — the regulator for English higher education
Last checked: September 2026. Reading and writing rates are from published meta-analyses, cited on the page.